Armchair Expert with Dax Shepard Nancy Segal (on twins)
Aug 20, 2025
Nancy Segal, an evolutionary psychologist and expert on twins, joins the conversation to unravel the mysteries of twin dynamics. She explains surprising insights from her work on twins raised apart, including how identical twins often mirror each other more than fraternal twins. The discussion spans topics like the unique genetic connections of twins, the emotional complexity of their relationships, and how their experiences challenge our understanding of identity and behavior. Prepare for a captivating dive into the science behind twinship!
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Firstborn Twin Birth Advantage
- Firstborn twins often have better immediate physical outcomes due to the delivery process rather than genetics.
- The delivery mechanics make the firstborn twin physically advantaged at birth but not determinative long-term.
The Jim Twins Spark A Study
- The Minnesota study began after the famous Jim twins (Jim Lewis and Jim Springer) were found and showed striking similarities despite separation.
- They shared bizarre parallels like hobbies, cars, and even first wives' names, sparking modern reared-apart twin research.
Colombian Switched Twins Case
- Nancy visited Colombian swapped twins raised in vastly different environments, from Bogota to remote La Paz, and studied their striking differences.
- Extreme rural nurture produced different education and vision outcomes strong enough to override genetic similarity on some measures.
